1. Field of the Invention
The invention relates to a system for delivering anesthesia drugs to a patient, the system comprising means for feeding anesthesia drugs to the patient treated, a measuring device for measuring at least one parameter relating to the effects of the anesthetic drugs fed to the patient, a patient monitor to show the results measured by the measuring devices, and feeding means for feeding patient demographics to the system.
2. Discussion of Related Art
Anesthesia is typically given (approximately 90% of the normal day surgery) by both intravenous and inhalational gas anesthetics. There exists however certain amount of users that practice total intravenous anesthesia (TIVA) especially in Europe and more widely TIVA can be used in small & fast cases. During the anesthesia anesthesiolgist titrates the anesthetics based on drug models and the drug distribution over time as well as by following the physiological parameters (the effect or responses to the drug given).
Intravenous (IV) drug distribution and model behaviour can be followed sometimes from an intravenous pump (IV pump) display (there exists some devices on the market, called TCI pumps) but in most of the cases there is no modelling or distribution shown. In practise the anesthesiologist still calculates an appropriate amount of drug for the particular patient with a calculator or in his head (the inputs being weight and height). This happens with the commonly used syringe pumps having no models inside them. Also the pumps are many times away from the parameter display (patient monitor) and so the effects and responses to the drugs are shown separately from the IV drug management.
The gas anesthetic statistical model called MAC (minimal alveolar concentration) is shown in most anesthesia monitors. This is however a quite approximative measure, since its background is on tests where the endpoint has been skin incision (and not for example the true hypnosis level). This measure is shown in some integrated anesthesia machines in the parameter display (patient monitor), so the anesthesiologist can see the drug effect and response quite easily. Another measure of gas anesthetics effect is the end tidal agent (ET) or fraction of inspired agent (FI), which can be shown in anesthesia monitor.
The first step to integrate the IV drug models into one display has been taken by GE Healthcare by launching a Care Assistant Suite (CAS) in European Anesthesiologist Congress 2005. This display shows IV drug models and their synergetic effects in one display, which is mounted next to the patient monitor and the anesthesia machine.
During the years several systems and methods have been developed in order to facilitate anesthesia drug deliveries. As typical examples of the solutions of the prior art the following publications can be mentioned.
PCT Publication WO0232036A2 describes a method and an apparatus for monitoring anesthesia drug dosages, concentration, and effects using N-dimensional representations of critical functions. This patent describes a method, system and apparatus for the monitoring, diagnosis and evaluation of the state of a dynamic system. The method and system provides the processing means for receiving sensed and/or simulated data, converting such data into a displayable object format and displaying such objects in a manner such that the interrelationships between the respective variables can be correlated and identified by a user. In particular, this invention is directed to the processing and display of drug data for the use of doctors in the process of monitoring or administering drugs to patients.
U.S. patent application 2003/0051737 A1 describes an apparatus and a method for titrating drug delivery. In this application a method and apparatus for reducing the workload of titrating drug (sedative, amnesic and & or analgesic) to effect while leaving clinician users in control of a related procedure is described. A drug delivery device is controlled to achieve a target drug concentration at a selected site in the patient or a predetermined infusion rate waveform. The time profile of the target drug concentration or a predetermined infusion rate waveform is controlled by a drug state model that uses clinical heuristics to implement safe, pre-defined changes in the target drug concentration or infusion rate and user-commanded changes in target drug concentration or infusion rate.
U.S. patent application 2002/0169636 A1 describes a system and method method for managing patient care. The application is directed to a system and method for providing care to a patient, comprising a patient care device having a number of configuration databases stored in a memory of the device. Each configuration database preferably includes protocols, operating limits, rule sets and/or operating features that collectively define an operating environment, or personality, of the device. The selected protocol includes default parameters for delivering the drug, and the label optionally includes instructions for deviating from the default protocol.
U.S. Pat. No. 6,631,291 describes a closed loop drug administration method and apparatus using EEG complexity for control purposes. A closed loop method and apparatus for controlling the administration of a hypnotic drug to a patient. At least one measure of the complexity of the EEG signal data is derived from the patient. An EEG signal complexity measure obtained from the cerebral activity of the patient can be advantageously used in conjunction with a measure of patient electromyographic (EMG) activity to improve the response time of hypnotic level determination and of the feedback control of drug administration. A pharmacological transfer function may be used, along with pharmacokinetic and pharmacodynamic models.
EP Patent Application 1 547 631 A1 describes a computer-controlled intravenous drug delivery system. The system described relates to controlling and steering intravenous anesthesia (IVA) and/or the application of other intravenous drugs to a patient in a safe and user friendly way. Less experienced anesthetists profit from expert knowledge stored, retrievable and usable via the system.
The systems and methods known in the prior art are however rather complicate and not so user friendly and flexible in every day life.